Pressurized fuel tank-DT300i

[CROSSBOLT]

Noticed on these last few really hot days the tank had a lot of pressure in it evidenced by the "whoosh" when the fill cap was removed. This was accompanied by quite hard starting. Had to "play" with the throttle to keep it running until it settled to a reliable idle. Even had a couple of bouts with surging idle which I have harped on Initialize to solve. Tested several times by removing the fill cap and heard the "whoosh" several times. Did a search on here for "pressurized fuel tank" and found a couple of posts. One solution was by Bettin' and Losin' out of Portland OR was to drill a small vent hole in the cap. His solution worked and the DT300i cap was even made for a vent! It just dint have the hole. The problem is CAUSED by the little vacuum valve that is SUPPOSED to open the tank vent line to the charcoal canister when the engine is started and running. This valve gets stuck and pressure rises on hot days even when running. I highly suspect this pressure is the cause of hard (flooded) starting and maybe surging idle. At any rate, the tank is no longer pressurized and the starts are Kymco reliable and easy. This system is used on most all bikes these days including the Buddy 150 by Genuine Scooter. That model had the notorious "Stall of Shame" that was fixed by venting the cap since the vacuum valves were unreliable. Those were carb engines with gravity feed and they would just "flame out" while riding.

Karl
 
PS: Checked with www.kymcopartsmonster.com for the valve and they want $34.xx for each!

[Stig / Major Tom]

I was troubled by a 'sucking' noise upon opening my LIKE's gas cap awhile ago.
Tank was forming a vacuum.
I played with all the hoses that came off the tank, and the plastic acorn sized valve thing.....sucking and blowing and fooling about with that valve, the hoses and the gas cap. Not knowing what I was doing.
But after I put it all back together again, everything worked fine and the tank started venting itself.
I think it was the cap that I magically fixed, so that it started venting.

This is how not to post a DIY.
Stig

[CROSSBOLT]

I'll bet what you did was to unseat that stuck valve by that sucking and blowing. That valve is the only way the tank can vent through the vapor can. The cap has no vent hole. This system seems to be common to all brands these days. I also had a vacuum situation on one of the cap removals and it was on a recent COOL morning, imagine that! That was kinda the proof for me the valve was stuck. This was the same way that Buddy acted way back. I could not unseat that one!

Karl

[CROSSBOLT]

Reminds me the wife's People GTi300 has the same system and has no problem like this tank pressurization and hard start stuff. Yet.....

Karl

[CROSSBOLT]

All is well so far....

Karl

[CROSSBOLT]

Almost forgot the UPDATE! Called he warranty lady at Howard's Motorcycles in Nashville to follow up on the warranty replacement of the vaccum valve that is stuck closed. She had ordered it from Kymco USA and she will mail it to me when it arrives. I will then exchange the valves and send her the original. Being about 150 miles from their shop helped with this arrangement. More as it develops.

Karl

[Stig / Major Tom]

Almost forgot the UPDATE! Called he warranty lady at Howard's Motorcycles in Nashville to follow up on the warranty replacement of the vaccum valve that is stuck closed. She had ordered it from Kymco USA and she will mail it to me when it arrives. I will then exchange the valves and send her the original. Being about 150 miles from their shop helped with this arrangement. More as it develops.

Karl

I keep hoping not to see the little picture attachment thing with your latest post on this subject.
Worried it might be a picture of a crater.

"pressurized fuel tank....."
Stig

[CROSSBOLT]

UPDATE: Warranty lady at Howard's Motorcycles, Nashville says the part will be sent to me today. The cynic in wife and me says, "Yeah, sure!" Will advise. This is after I called this am to follow up.

Karl

[CROSSBOLT]

UPDATE: No info from Howard's, the warranty lady and nothing in the mail. Called Kymco USA for number/e-mail of Kymco rep for Nashville. Sent Rob Slover a nice e-mail outlining the events. I did this because I thought I was getting the standard issue RUNAROUND! Be very surprised if anyone at dealer did ANYTHING! Will advise.

Karl

[Stig / Major Tom]

Sorry to hear this Karl.
Hang in there. ...Mr. Slover is on the case now!
Good luck.
Regards
Stig

[CROSSBOLT]

Gotta eat some of my words! The valve showed in the mail late this pm! All other gripes stand. Sent message to rep to this effect. Thanks, Stig.

Karl

[CROSSBOLT]

CONCLUSION: Takes about a minute to replace the valve but it takes HOURS AND HOURS to remove/replace body panels! Recommend forget about valve and just drill hole in cap for vent. The valve and canister are buried forward and under front of fuel tank below fuel tank mid-point. This valve is gonna fail especially with ethanol fuel (opinion). There seems no downside of valve being permanently closed for the rest of evap system if tank is vented through the cap. There is NO info in service manual as to where these components are and I doubt any service dept at any dealer would take the time (hours and hours) to get to it even if they knew where the valve and vapor can were. I would posta picture of where hole should be drilled in DT300i fuel cap if I hear enough begging!

Been on several rides since it got hot again and suffered no symptoms of pressure in tank or hard starting or "wonky" idle. I have NO idea why Initialize would correct the surging idle if caused by pressure in fuel tank.

Karl

[Stig / Major Tom]

CONCLUSION: Takes about a minute to replace the valve but it takes HOURS AND HOURS to remove/replace body panels! Recommend forget about valve and just drill hole in cap for vent. The valve and canister are buried forward and under front of fuel tank below fuel tank mid-point. This valve is gonna fail especially with ethanol fuel (opinion). There seems no downside of valve being permanently closed for the rest of evap system if tank is vented through the cap. There is NO info in service manual as to where these components are and I doubt any service dept at any dealer would take the time (hours and hours) to get to it even if they knew where the valve and vapor can were. I would posta picture of where hole should be drilled in DT300i fuel cap if I hear enough begging!

Been on several rides since it got hot again and suffered no symptoms of pressure in tank or hard starting or "wonky" idle. I have NO idea why Initialize would correct the surging idle if caused by pressure in fuel tank.

Karl

I'd like to see a picture, please, of the cap, your best looking dog or even that pretty white scooter !
Do you drill the hole in the cap in-situ ? or do you remove the cap to a safe place?
Thanks, Stig

[mnpugdog]

Yes please post a pic for us Karl

[CROSSBOLT]

OK, that's pretty good begging! I will do it! Tomorrow or Thursday. Ya gotta take the cap off and apart to drill the hole. It should be a nice project!

Karl
 
PS: Was pre-empted by "honey-do's" but WILL post pictures soon! Promise! Check's in the mail.....